View source for HMG-box

{{Short description|Protein domain which is involved in DNA binding}}
{{Infobox protein family
| Symbol = PF00505
| Name = HMG (high mobility group) box
| image = 2LEF.png
| width = 300px
| caption = [[Protein nuclear magnetic resonance spectroscopy|NMR structure]] of the HMG-box domain of the [[Lymphoid enhancer-binding factor 1|LEF1]] protein (rainbow colored, [[N-terminus]] = blue, [[C-terminus]] = red) complexed with DNA (brown) based on the {{PDB|2LEF}} coordinates.
| Pfam = PF00505
| Pfam_clan = CL0114
| ECOD = 190.1.1
| InterPro = IPR009071
| SMART=
| PROSITE=
| SCOP = 1hsm
| TCDB =
| OPM family =
| OPM protein =
| PDB = {{PDB2|1aab}}, 	{{PDB2|1cg7}}, 	{{PDB2|1ckt}}, 	{{PDB2|1e7j}}, 	{{PDB2|1gt0}}, 	{{PDB2|1hme}}, 	{{PDB2|1hmf}}, 	{{PDB2|1hry}}, 	{{PDB2|1hrz}}, 	{{PDB2|1hsm}}, 	{{PDB2|1hsn}}, 	{{PDB2|1i11}}, 	{{PDB2|1j3x}}, 	{{PDB2|1j46}}, 	{{PDB2|1j47}}, 	{{PDB2|1j5n}}, 	{{PDB2|1k99}}, 	{{PDB2|1lwm}}, 	{{PDB2|1nhm}}, 	{{PDB2|1nhn}}, 	{{PDB2|1o4x}}, 	{{PDB2|1qrv}}, 	{{PDB2|1s9m}}, 	{{PDB2|1sx9}}, 	{{PDB2|1v64}}, 	{{PDB2|1wgf}}, 	{{PDB2|1wxl}}, 	{{PDB2|2crj}}, 	{{PDB2|2cs1}}, 	{{PDB2|2lef}}
}}
In [[molecular biology]], the '''HMG-box''' ('''h'''igh '''m'''obility '''g'''roup box) is a [[protein domain]] which is involved in [[DNA-binding domain|DNA binding]].<ref name="pmid17599239">{{cite journal |vauthors=Stros M, Launholt D, Grasser KD | title = The HMG-box: a versatile protein domain occurring in a wide variety of DNA-binding proteins | journal = Cell. Mol. Life Sci. | volume = 64 | issue = 19–20 | pages = 2590–606 |date=October 2007 | pmid = 17599239 | doi = 10.1007/s00018-007-7162-3 | s2cid = 28156847 | pmc = 11136187 }}</ref> The domain is composed of approximately 75 amino acid residues that collectively mediate the DNA-binding of chromatin-associated high-mobility group proteins. HMG-boxes are present in many transcription factors and chromatin-remodeling complexes, where they can mediate non-sequence or sequence-specific DNA binding.<ref>{{cite journal |last1=Štros |first1=M. |last2=Launholt |first2=D. |last3=Grasser |first3=K. D. |title=The HMG-box: a versatile protein domain occurring in a wide variety of DNA-binding proteins |journal=Cellular and Molecular Life Sciences |date=October 2007 |volume=64 |issue=19–20 |pages=2590–2606 |doi=10.1007/s00018-007-7162-3 |pmid=17599239 |url=https://link.springer.com/article/10.1007/s00018-007-7162-3 |access-date=18 February 2023|pmc=11136187 }}</ref>
==Structure==
The structure of the HMG-box domain contains three [[alpha helix|alpha helices]] separated by loops (see figure to the right).<ref name="pmid11497996">{{cite journal | author = Thomas JO | title = HMG1 and 2: architectural DNA-binding proteins | journal = Biochem. Soc. Trans. | volume = 29 | issue = Pt 4 | pages = 395–401 |date=August 2001 | pmid = 11497996 | doi = 10.1042/BST0290395}}</ref>
==Function==
HMG-box containing proteins only bind non-[[B-DNA|B-type DNA]] conformations (kinked or unwound) with high affinity.<ref name="pmid17599239"/>  HMG-box domains are found in some [[high mobility group]] proteins, which are involved in the regulation of DNA-dependent processes such as [[transcription (genetics)|transcription]], [[DNA replication|replication]], and [[DNA repair]], all of which require changing the [[conformational isomerism|conformation]] of [[chromatin]].<ref name="pmid11497996"/>
The single and the double box HMG proteins alter DNA architecture by inducing bends upon binding.<ref>D. Murugesapillai ''et al'', [https://doi.org/10.1093/nar/gku635 DNA bridging and looping by HMO1 provides a mechanism for stabilizing nucleosome-free chromatin], Nucleic Acids Res (2014) 42 (14): 8996-9004</ref><ref>D. Murugesapillai ''et al'', [https://link.springer.com/article/10.1007/s12551-016-0236-4 Single-molecule studies of high-mobility group B architectural DNA bending proteins], Biophys Rev (2016) doi:10.1007/s12551-016-0236-4</ref>
==References==
{{Reflist}}
==External links==
* {{MeshName|HMG-Box+Domains|3=HMG-Box Domains}}
[[Category:DNA-binding substances]]
[[Category:Protein superfamilies]]
[[Category:Protein domains]]
{{Protein-stub}}